Imidazole derivatives inhibiting nf sarcoma

ABSTRACT

Imidazole derivatives of the formula (I)   wherein R1 is lower alkanoyl, and R2 and R3 are each lower alkanoyl or jointly lower alkylidene are readily prepared by reaction of formic acid with corresponding starting compounds having an amino group in position 5 of the imidazole ring, and hydrogen or lower alkanoyl groups instead of each of R1, R2, R3 or alkylidene in R2 and R3. They inhibit the growth of NF sarcoma in mice.

United States Patent Yamazaki et a1.

[451 July 18,1972

[54] IMIDAZOLE DERIVATIVES INHIBITING NF SARCOMA [72] Inventors: AkihiroYamazaki; Teruo Furuknwa;

- lzumi Kumashiro, all of Kanagawa, Japan [73] Assignee: Ajinomoto Co.,Inc., Tokyo, Japan [22] Filed: Feb. 27, 1970 [21] Appl. No.: 15,245

Noller Chemistry of Organic Compounds 3rd. Ed. 1965, pp. 186 and 268, W.B. Saunders Co., Philadelphia, Pa.

Primary Examiner-Lewis Gotts Assistant Examiner-Johnnie R. BrownAuorney-Kelman and Berman ABSTRACT Imidazole derivatives of the fonnula(l) wherein R is lower alkanoyl, and R and R are each lower alkanoyl orjointly lower alkylidene are readily prepared by reaction of formic acidwith corresponding starting compounds having an amino group in position5 of the imidazole ring, and hydrogen or lower alkanoyl groups insteadof each of R,, R R or alkylidene in R and R They inhibit the growth ofNF sarcoma in mice.

4 Claims, No Drawings I-l o o I I iii wherein R is lower a lkanoyl, andR, and R, are each lower alkanoyl or jointly lower alkylidene.

Representative compounds of the invention are identified belowby capitalletters, and will be referred to by such letters hereinafter for thesake of brevity:

pound of the formula (11) X- O-CH- wherein X is hydrogen or loweralkanoyl, Y and Z are each hydrogen or lower alkanoyl, or jointly arelower alkylidene.

Preferred starting compounds of the formula (ll) include:-amino-4-thiocarbamoy1- 1 -B-D-ribofuranosy1-imidazole,5-amino-4-thiocarbamoy1-l-(2',3'-O-isopropylidene B-D-ribofuranosyl)-imidazole,

S-ami no-4-thiocarbamoyll 2 ,3 '-O-isopropylidene-5 '-O-acetyl-B-D-ribofuranosyl)-imidazole, 5-amino-4-thiocarbamoyll 2 ,3 ',5'-tri-O-acetyl-B-D-ribofuranosyl )-imidazole,

and others will readily suggest themselves to those skilled in the art.

The compounds of formula (11) are reacted with fomiic acid or with asalt of formic acid in the presence of an acid stronger than formicacid. The alkali metal, ammonium and alkaline earth metal formates aremost conveniently available and preferred for this reason. They may beused in conjunction with hydrochloric, sulfuric, nitric or phosphoricacid, to name only the least expensive and readily available acidssuitable for the purpose.

The water formed by the reaction is preferably removed.

When the reaction is performed at ambient temperature of 5 to 30C, thereactants are dispersed in a dehydrating solvent 2 for water. vWhen thereaction is performed at elevated temperature, a solvent is not needed,particularly if the reaction mixture is at its boiling point.

An excess of formic acid over the stoichiometrically equivalent amountof the compound of formula (11) is preferred, whether the formic acid isadded to the reaction mixture as such or formed in situ from a fonnateand a stronger acid. Thus, more than 4 moles formic acid should bereacted with one mole of TAICAR, and more than 2 moles of formic acidwith one mole of 5-arnino-4-thiocarbamoyl-l- The compound of formula (I)is readily recovered from the reaction mixture in pure form byprecipitation, solvent extraction or chromatographic methods. A solidreaction product may be filtered from the other constituents of themixture and purified by washing with a suitable solvent. When thedesired product is dissolved, the reaction mixture may be evaporatedrepeatedly in the presence olan alcohol, and then treated with activatedalumina for recovering the compound of the invention.

The-compounds of the invention are more efiective against NF sarcoma inmice than 6-mercaptopurine while being less toxic, and are surprisinglysuperior to chemically closely related compounds as is evident from acomparison made between Compound A,5-formamido-4-thiocarbamoylimidazole,5-acetylamido-4-thiocarbamoylimidazole-1-(2',3',5-tri-o-acetyl-B-D-ribofuranosyl)-imidazole, and 6 -mercaptopurin. 1nthe comparison tests, Swiss albino mice were given subcutaneousinjections of NF sarcoma. 24 hours afier the injection and dailythereafter for a total of 5 days, respective groups of mice wereinjected intraperitoneally with 30 mg/kg of the four compounds tested.After 10 days, the tumors were excised and weighed, and theeffectiveness of the injected compounds was detemiined by comparisonwith tumors of otherwise similar mice which did not receive treatmentafter injection of the sarcoma. The percentage values listed in Table 1below indicate that the average weight of the tumors in mice injectedwith Compound A was only 3 percent of the average tumor weight inuntreated mice.

TABLE 1 Compound Percent Compound A 5-fonnamide-4-thiocarbamoylimidazolel 5 s-acetylamino-l-thiocarbamoyl-l 2 ,3',5'-tri-0acetyl-fi-D-ribofuranosyl )-imidazole 1 27 fi-mercaptopurine 9 CompoundB 5 The value LD for Compound A as determined in mice which survived 14days after the intraperitoneal injections was 3.11 millimoles per kg(1,200 mg/kg) while it was 1.20 millimole per kg (205 mg/kg) foro-mercaptopurine.

The following examples are further illustrative of the compounds of theinvention, and of the methods of preparing the same.

EXAMPLE 1 Calculated forC, H N,O,,S: 40.41%C 3.65%H 14.50%N

Found: 40.66 3.42 14.35 Melting point: C (decomp.)

UV absorption spectrum: A EtOl-l 289 and 337.5 mp.

max

IR absorption spectrum: 1700 cm" C O) 1 g-Amino-4-thiocarbamoyl-l-(2,3',5'-tri-o-acetyl-B-D-ribofuranosyD-imidazole was dissolved in a mixture of 40 ml formic acidand 20 ml acetic anhydride, and the solution was kept ovemight at roomtemperature. Methanol was added until a substantially clear solution wasobtained, and the solution was evaporated to dryness in a vacuum. Theresidue was again dissolved in methanol, and the solution evaporated todryness, and this procedure was repeated several times. Ultimately, theresidue was dissolved in ml chloroform, and the chloroform solution waspassed through a column packed with activated alumina. The column waseluted with a mixture of benzene and ethyl acetate, and the eluate wasevaporated to dryness in a vacuum. 5 19 mg compound B were obtained (42percent yield). It had a melting point of 58C and was identified by itselementary analysis:

Calculated for C H O N S: Found:

The UV spectrum showed values of A EtOH at 290 and 329 mg, and thespecific rotation was [111 =+90 (C 1 pyridine).

Compounds C and D are prepared in a manner obvious from Examples 1 and2. Experiment 1. Production of 5-amino-4-thiocarbamoyl-l-(2,3'5-tri-o-acetyl-B-D-ribofuranosyl) -imidazole 3.2 g5-amino-4-carbamoyl-l-(2',3',5'-tri-o-acetyl-B-D-ribofuranosylfimidazole was dissolved in 40 ml pyridine with heating, tothe resultant solution l.97 g phosphorus pentasultide was graduallyadded with stirring while heating on an oil bath of 120C, and themixture was stirred for further 2 hours. Pyridine was evaporated underreduced pressure, residues obtained were dissolved in 50 ml water, andafter treated with active charcoal recrystallization from water wasrepeated twice. Pure crystals of 5-amino-4-thiocarbamoyl-1-(2',3,5'-tri-o-acetyl-B-D-n'bofuranosyl)imidazole obtained weighed 1.05 g.

DH l mu all 13 mu- 3. Rfvalue: 0.69 on a paper chromatogram developedwith nbutanol acetic acid :water=4: l :l system (parts by 278 and 327my. 240, 273 and 324 mp.

volume) 4. Elementary analysis:

C(%) H(%) N(%) Found 45.18 5.04 l3.84 Calculated for 44.99 5.03 13.99 raznq l Experiment 2. Production of 5-amino-4-thiocarbamoyl-l-(2',3'S-O-acetyl-p-D-ribofuranosyl)- imidazole 1 L98 g5-amino4-carbamoyl-l-(2,3-O-isopropylidene-5'-acetyl-B-D-rihofuranosyl)imidazole was dissolved in I70 ml pyridine,8.29 g phosphorus pentasulfide was added, and reacted as in the way asin Experiment 1. Solvent was evaporated from the reaction mixture,residues obtained were dissolved in 200 ml water, and treated with 200ml chlorofomi. The chloroform layer was washed with water, chloroformwas evaporated, and resultant residue was dissolved in I00 ml methanol.10 ml concentrated ammonia was added to the methanol solution, and themixture was stirred for 2 hours at room temperature. Methanol waseveporated. to the residue picric acid saturated ethanol solutioncontaining 2.5 g picric acid was added, and crystals precipitated wereisolated by filtration. The crystals were recrystallized from ethanol,and pure crystalline 5-amino-4-thiocarbamoyl-l-(2',35'-O-acetyl-B-D-nbofuranosyl)imidazole picrate was obtained in anamount of 5.36 g. The crystal melted at 194 195C (decomposed).

What is claimed is:

l. A compound of the formula R2 iii:

wherein R is lower alkanoyl, and R and R; are each lower alkanoyl orjointly lower alkylidene.

2. A compound as set forth in claim 1, wherein said alkanoyl is fomtylor acetyl.

3. A compound as set forth in claim 1, wherein said R R and R is formyl.

4. A compound as set forth in claim 1, wherein each of said R,, R and Ris acetyl.

2. A compound as set forth in claim 1, wherein said alkanoyl is formylor acetyl.
 3. A compound as set forth in claim 1, wherein said R1, R2and R3 is formyl.
 4. A compound as set forth in claim 1, wherein each ofsaid R1, R2 and R3 is acetyl.